JPEG image quality

Hello,
In DJI Go I always use J+R with my P3P, jpeg and raw pictures. Quality is reasonably good.
Today I started my first mission.
I see I only can adjust exposure compensation which is -0.3 by default.
You suggest to avoid extreme highlights and darkness, let's say, high contrast but you change style to +3 +3 +2 (sharpness, contrast, saturation).
I understand that for stitching purposes you need sharpness, but also contrast and saturation? High contrast flattens dark and light areas.
In my test I found a large amount of solid black areas. It is easy to see in the histogram.
I also see still areas that weren't stitched well.
I would like to take the photos in raw format and then apply the same filters/correction to them.
Very good all the option you offer to download after post-process

Daniel Stonek 18 أكتوبر، 2015 19:43

تعليق رسمي

Most map processing softwares rely on the EXIF tags that are embedded within JPG images. This information includes sensor geometry, focal length, and GPS location when available. RAW images are not suitable for map stitching.

We have placed the default sharpness, contrast and saturation numbers where they are based on lots of testing.

The saturation number is the one that affects color and we have left that adjustable because of how the cameras respond to different color situations like green grass vs white desert.

For a sunny day, be sure to select "Sunny" as the White Balance setting.

Cameras can only resolve a certain amount of dynamic range. That contrast setting isn't going to change that.

Stitching will certainly suffer when there are saturated (white) or shaded (dark) areas in the imagery. When a camera is accepting too much light no matter what you do, the only thing left to do is use an ND filter to squeeze the scenes dynamic range down to a range that can be captured. This will likely require slowing the flight down a bit too.

Please refer to www.mapsmadeeasy.com/data_collection for more details.

Tudor 19 أكتوبر، 2015 16:44

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5 تعليقات

Hi, I meant to take RAW images and let us apply the same filters to all of them, save them in jpeg and finally upload them to stitching process.
In White Balance I have a fixed value of 5200ºK. I found this app changed it to 'sunny'.
I suppose it is a DJI matter to let users save camera configurations.
It is annoying to have to manually go back to previous settings when using GO app.

"Cameras can only resolve a certain amount of dynamic range. That contrast setting isn't going to change that"
The problem is not the dynamic range in the camera, it is the tonal range in the output that is reduced increasing the contrast.
That's why I'm asking to to shoot RAW, edit and then upload JPEGs.

I1 and P3P's camera have a 1/8000 sec f1:2.8 minimum EV. I think ND filters are needed in rare cases.
Thanks.

Daniel Stonek 19 أكتوبر، 2015 19:16 0 أصوات

The RAW images do not contain the tags we require for processing. You cannot add the required data after the fact. RAW may have more and better pixel information but it doesn't have positional information that is required for spatial processing.

We will look at how we have the contrast value set.

Map Pilot sets the White Balance to whatever the setting is set to. We default to Auto which will apply what it thinks is the best setting for the conditions just as DJI does.

Tudor 19 أكتوبر، 2015 19:37 0 أصوات

All my JPEGs I've gotten from DNG P3P photos have location data.

Lens Info : 20.7mm f/?
Lens Model : 20.7 mm
GPS Version ID : 2.3.0.0
GPS Latitude Ref : South
GPS Longitude Ref : West
GPS Altitude Ref : Above Sea Level

Aperture : 2.8
Date/Time Created : 2015:10:14 08:54:05
Digital Creation Date/Time : 2015:10:14 08:54:05
GPS Altitude : 79.7 m Above Sea Level
GPS Latitude : 34 deg 33' 10.49" S
GPS Longitude : 56 deg 45' 16.55" W
GPS Position : 34 deg 33' 10.49" S, 56 deg 45' 16.55" W
Image Size : 3949x2932
Megapixels : 11.6

Exif data is wider than original jpeg file because it contains camera raw edition data

Daniel Stonek 19 أكتوبر، 2015 21:37 0 أصوات

We'll look into adding it but it is not a high priority. It also seems to drop the maximum frame rate down to just under 5s which is probably why DJI has their intervalometer set the way it is. That will severely limit the speed the aircraft can fly and the amount of ground it can cover on a battery.

Tudor 19 أكتوبر، 2015 22:03 0 أصوات